#include<bits/stdc++.h>
#define ONLINE_JUDGE
#define ll long long
#define ull unsigned long long
using namespace std;

const int N = 1e6 + 10, INF = 0x3f3f3f3f;

int n, m, k;

void solve()
{
    priority_queue<int, vector<int>, greater<int>> q;
    cin >> n >> m >> k;
    for (int i = 1;i <= n;i++) {
        int x;cin >> x;
        q.push(abs(x - k));
    }
    m--;
    while (m--) q.pop();
    cout << q.top() << '\n';
}

signed main()
{
    // ios::sync_with_stdio(0);
    // cin.tie(0);cout.tie(0);
#ifndef ONLINE_JUDGE
    std::istringstream in(R"()");
    std::cin.rdbuf(in.rdbuf());
#endif
    int T = 1;
    cin >> T;
    for (int i = 1;i <= T;i++) {
        solve();
    }
}